audio production ch4

what is the first device in our sound chain

microphone

what is a sound chain

everything in the system we are using

what is a microphone

a transducer that changes sound waves into electrical signals

is there a perfect mic that can be used for every situation

no; different mics are suited for particular sounds, instruments, etc.

why is selection and placement important and why should you experiment with it

poor placement can cause expensive and top quality mics to sound bad; you never know what is going to sound the best until you try it and perfect placement changes for every environment and instrument

what are the three types of mics

dynamic, ribbon, and condenser

what is a dynamic microphone

mic that uses electromagnetic induction to transduce sound into an audio signal through a thin diaphragm, voice coil, and a magnetic field

how does a vast majority of electricity we use get produced

through the application of the theory of electromagnetic induction

how does a dynamic mic work (physical makeup)

a voice coil made of wire is attached to a thin plastic diaphragm, the coil moves back and forth around a magnet when the air pressure of sound waves changes which pulls on the diaphragm. the movement of the coil through a magnetic field causes electricity to be generated

what are the characteristics of a dynamic mic

more durable than condensers and ribbons, not as flat in their frequency response as condensers, emphasize mid-range frequencies, not as sensitive to sound as condensers, can handle very loud sounds, and requires no phantom power

how do changes in amplitude or frequency affect the dynamic mic

louder the sound, higher the level of voltage created by the mic and vice versa; higher frequencies cause the diaphragm to vibrate faster and changes in the electric signal are also faster

what are ribbon mics

mics that use electromagnetic induction to transduce sound into an audio signal by using a strip of extremely thin aluminum that is corrugated

how do ribbon mics work ([physical makeup)

a strip of extremely thin aluminum that is stretched out is suspended within a strong magnetic field where sound pressure variations cause it to move and cut across the magnetic flux lines and generate electricity

what are the characteristics of ribbon mics

produce a “warm” pleasing sound to the ear, roll off high frequencies and don’t pick them up well, are very delicate and easy to break, require no phantom power because it melts the ribbon, and can be more accurate than dynamic mics but not as accurate as a condenser

what is a condenser mic

mics that operate on an electrostatic principle rather than the electromagnetic principle used by dynamics and ribbons

how does a condenser work (physical makeup)

the capsule of a condenser mic consists of a very thin and movable diaphragm and one fixed backplate which form a capacitator, and when a sound moves through the diaphragm it changes the capacitance of the capsule (its ability to store electricity)

what is a capacitator

a device that can store electricity

what is phantom power

a direct current voltage that is sent through a mic cable to power the active circuitry of a condenser mic

what are the characteristics of a condenser

the most accurate type of mics, have a flatter frequency response than dynamic and ribbon mics, are more sensitive than dynamic and ribbon mics, require phantom power, and are not as rugged as dynamic mics

what is directional response

a mics ability to pick up sound from some directions and to reject sound coming from other directions

what does on axis refer to

the direction a mic is most sensitive to sound

what does off axis refer to

the angles a mic is least sensitive to sound

what are polar patterns and the other name they are known by

aka pickup patterns; a graph that shows how well a mic picks up sound from all angles

what are the four types of polar patterns

cardioid, hyper cardioid, directional, and omnidirectional

what is a cardioid pattern

picks up sound in a heart shape to the front of the mic and rejects sound progressively more towards the back of the mic

what is a hyper cardioid pattern

picks up sound in a narrower heart shape area in front of the mic and has a small area of sensitivity to the rear

what is a directional/figure 8 pattern

picks up sound from the front and the rear and rejects sound from the sides

what is an omnidirectional pattern

picks up sound from all directions

all true ribbon mics are ____________

bidirectional

what is microphone frequency response

the ability of a mic to pass frequencies through itself in comparison to the frequencies in the sound wave it captured

what is flat frequency response

when all frequencies pass through a mic at the same relative levels they were in the sound wave

is it possible for a mic to have a perfectly flat frequency response

no

what is transient response and what can it do

how quickly and accurately a mic can react to a sound; can vary a great deal from one type of mic to another and can change the character of a sound based off the difference in transient responses of different mics

what are the common mic pickup issues besides transient response and frequency response

low frequency rumble, proximity effect, popping, and off-axis pickup

what is low frequency rumble

when low frequency and high level vibrations are picked up by mics and distort sound quality

how can low frequency rumble be eliminated

choosing a mic that doesn’t pick up low frequency well, use a mic with low frequency roll off filters, or use a shock mount to isolate the mic from vibrations

what is proximity effect

when a directional mic is brought closer to the sound source and picks up more low end frequencies

what type of mic has no proximity effect

omnidirectional

what is popping and how can it be eliminated

when mics are exposed to wind or breath blasts like on letters such as P, T, or B; place a pop filter between the artist and the mic, turn the mic slightly off axis, or replace the directional mic with an omnidirectional mic

what is off axis pickup and how can it be reduced

the loss of higher frequencies in sound coming from the directions that the mic is less sensitive to; angle a directional mic away from the sound source

what are the output charcteristics

sensitivity, equivalent noise (self noise), overload, and mic impedance

what is sensitivity

the output of a mic in volts compared to the input in SPL

what is equivalent noise/self noise and how can you balance it

noise created by the mic itself; when recording a sound with a wide dynamic range, use a mic with low equivalent noise rating so you don’t hear that noise during quiet passages

what is overload and which mics can handle it/can’t handle it

distortion from a sound too loud for the mic to handle; dynamics can handle louder sounds and condensers distort sooner because they are more sensitive

what is microphone impedance

an electrical rating that helps match the output of a mic to the input of a microphone preamp

what is the most often neglected link in the sound chain that leads to poor sound quality

cables and damaged cables

why are cables important

the voltage is the lowest level signal we deal with in audio and that makes them easily diminished

what is the difference between balanced and unbalanced cables and which one is better to use

balanced cables have at least 3 conductors/wires while unbalanced cables have just two wires; balanced cables are better because they reduce interference in signals

what does having a third wire in a cable allow you to do

allows for the cancelation of interference

what do ground cables do

help shield the two conductors from interference

what are some of the parts of a high quality wire

oxygen free copper, twisted pairs of conductors, braided or twisted copper shields that completely envelopes the conductor, and internal reinforcements that protect the wire strands from breaking

what are some high quality connectors

Switchcraft, Neutrik, and Amphenol

what are some tips for cable usage

use high quality wire, high quality connectors, as short of cables as possible, wrapping cables without twisting them, not allowing cables to be walked on, and occasionally clean the connectors

what are XLR connectors

the most commonly used method to connect mics to preamps, mixers, interfaces, and line-level devices

what are quarter inch connectors

used to interface between both professional and semi-pro equipment at line-level

what are TT/bantam connectors/cables

cables that allow balanced lines to be plugged into a patch bay for fast and easy access to the various line-level devices

what are microphone preamps

gain devices that raise the low output voltage of mics up to the higher line level voltage and can have different sonic characteristics

what are solid state preamps

more transparent (accurate) and can produce much less noise, distortion, and coloring than preamps with tubes in their gain stage

what are tubes

preamps that can create very pleasant even-order harmonic distortion that results in warm tones and coloring that solid state preamps can not produce